Removal of content of body cavities by suction is well known in medical practice. There are several apparatuses known for carrying out operations with a vacuum method. For example the system of English Pat. No. 1,273,387 for gynecological purposes is based on the principle of suction. In essence the catheter is connected with a container provided with a filter, which also serves as the handle of the instrument.
A drawback of this system is that the material drawn from the cavity can not be observed in practice. Owing to the fast rate of coagulation, separation of the tissue parts and clotted blood does not take place in spite of the filtering either. No provision is made either for the fixing and disinfection of the tissue parts, preferably with formalin, which can be necessary for subsequent--e.g. microscopic--examination.
Replacement of the catheter, which is necessary in some cases cannot be carried out or is carried out only with difficulty with the simultaneous removal of the container cover. The device does not permit cytological sample taking with identical instrument.
Another well-known apparatus is described in U.S. Pat. No. 3,721,244. Its drawback in addition to those already mentioned, is that the catheter is not replaceable at all.
Another disadvantage is that the cervix may have to be previously dilated in relation to the diameter of the catheter. This can be a main cause of subsequent gynecological complaints by the patient, especially in case of an injured cervix.
Thus a disadvantage of the instruments known so far is that they do not perfectly separate the material removed from the cavity and necessary for the subsequent examination from the unnecessary other material, e.g. from the blood; direct observation of the materials removed from the cavity is not available or is difficult; further preparation, e.g. fixing of the tissues for instance for subsequent microscopic examination, is not possible. In addition, generally little consideration is given to the necessity of careful treatment of the cervix; replacement of the catheter during operation is not possible or is difficult to achieve; and simultaneous cytological sample taking is not possible in the course of the operation.
We know of no suction system which, besides filtering the biopsy material obtained from the cavity, facilitates by any other means its direct examination with the eye, and enables its immediate preparation for further examination. This is highly significant, especially in gynecological practice, where the careful inspection of the removed endometrium may decisively influence the further course of the operation. The immediate washing of the withdrawn material is necessary for the inspection. The immediate preparation of the material for histological examination significantly increases the reliability of the examination.
Highly significant among the suction catheters are those, which are used for intrauterine gynecological suction catheters. The medical practice has special requirements concerning the gynaecological suction catheters. The end of a suction catheter should be able to pass a catheter through the cervix after minimal dilation and without injury. Injury of the cervix is very frequent, causing premature births, subsequent sterility and cancerous diseases. At the same time, for removal of the more persistently sticking materials an edge should be provided by which the removal of the endometrium persistently adhering to the rear wall of the uterus, can also be ensured. At the same time it is essential that the suction catheter should not cause injury, e.g. perforation of the uterus.
In this respect the above described systems are not satisfactory. The suction catheter according to U.S. Pat. No. 3,721,244 does not have an edge and its passage through the cervix is free, from risk of injury. This is also true in the apparatus of the English Pat. No. 1,273,387, in which the handle of the catheter is the collecting container itself.
Thus it is apparent that the known rigid suction catheters do not solve the mentioned problems. Although an edge can be provided on the instruments made from metal, the rigidity of the catheter frequently leads to injury of the uterus. For this reason flexible suction catheters, such as the flexible catheters of U.S. Pat. No. 3,506,010 have become popular. This arrangement considerably reduces the risk of injury, although the flexible material does not allow a rigid edge to be formed; thus these instruments are not suitable for sample taking, or for the removal of persistently sticking materials.